Microfluidic sensor for semi-quantitative E. coli monitoring in water samples

Escherichia coli (E. coli) is a gram-negative bacteria from the Enterobacteriaceae family commonly found in the lower intestines of animals and humans in a mutually beneficial association, but on rare occasions it can cause disease [1-3]. The infection in humans usually results from contact with contaminated water sources and it can result in severe and even life-threatening infection. The contamination of water sources can be due to contact with human or animal feces; it can be especially critical in developing countries where access to safe drinking water is scarce [1-2]. The infection with E. coli can cause enteritis, urinary tract infection, septicemia, and is also associated with diarrhea. In fact, in 2017, over six hundred thousand deaths caused by diarrheal diseases in Sub-Saharan Africa were reported [4], which reinforces the importance of monitoring enteric pathogens such as E. coli. Recently, the interest in the development of sensors for simple, on-site, rapid testing has been increasing. These sensors are expected to be produced in a low-cost manner, without the need of complex and expensive equipment. Additionally, they have the potential to be user-friendly, enabling their use by non-specialized personnel. In this context, lateral flow strips, as a microfluidic paper-based platform, have proven to have a huge potential to carry out simple testing [4] and can be a promising technique for targeting E. coli. In this work, the objective is to develop a lateral flow assay (LFA) strip as a biochemical sensor for the semi-quantification of E. coli in potentially contaminated drinking water sources. This sensor is based on the amplification of the DNA of the pathogen, using the loop-mediated isothermal amplification technique (LAMP), and a newly designed lateral flow strip.